The basic principles of induction heating have been known for quite some time. It has heretofore been known to utilize power sources including rectifiers and inverters in order to drive an induction heating coil, thereby producing an alternating magnetic field which is coupled through a planar cooling surface to a cooking pan in order to provide cooking action. Examples of such previously developed induction cooking systems may be found in U.S Pat. No. 3,637,970 issued to Cunningham on Jan. 25, 1972 and entitled "Induction Heating Apparatus"; U.S. Pat. No. 3,697,716 issued to Kornrumpf on Oct. 10, 1972 and entitled "Induction Cooking Power Converter with Improved Coil Position" and U.S. Pat. No. 3,823,297 issued to Cunningham on July 9, 1974 and entitled "Load Controlled Induction Heating". It has also been known to utilize touch control devices to control the operation of such induction cooking devices.
Previously developed induction cook-top devices have not provided adequate control systems for controlling the energization, deenergization and variation of heating levels of induction heating coils. Lack of such control introduces unsafe operating conditions in the use of induction cook-top devices. For example, one such unsafe operating characteristic observed in prior art induction cook-top devices has been the inability to decrease a heating level of an induction heating coil when the induction heating coil is operating at a high level and the operator is in physical contact with the cooking pan or a utensil, such as a spoon, inside the cooking pan. The operator must therefore remember not to touch the cooking pan or a utensil in order to decrease the heating level or shut off an induction heating coil. This operating requirement makes the operation of induction cooking devices cumbersome and hazardous. Consequently, a need has arisen for an induction cook-top system which is economical to manufacture and simple in operation, including touch controls that are accurate to safely control heating levels and energization of the system.